Expansible rimmed abrading wheel



Jan. 17, 1950 E. KRISTEK EXPANSIBLE RIMMED ABRADING WHEEL Filed May 7,1948 Patented Jan. 17, 1950 UNITED STATES PATENT OFFICE assignor toBata, Naro Slovakia dni Podnik, Zlin, Czecho- Application May 7, 1948,Serial No. 25,654 In Czechoslovakia May 5, 1947 The present inventionrelates to rotary. grinding, polishing, cleaning or similar abrasiverollers, discs and the like provided with an emery cloth or emery papercoating, and more particularly to a method and arrangement for ten-.

to the abutting faces of the two parts in the.

open position of the latter, the coating being tensioned by closing thesaid parts. In other cases a one piece disc or wheel is used providedwith a groove in which the ends of the coating are retained by means ofsome mechanical contrivance. Both arrangements result in an uneconomicalutilisation of the abrasive layer because the latter must be providedwith folded over portions at both ends to permit the fastening andtensioning of the coating on the periphery of the disc, and moreover thewear is considerably greater in those portions of the periphery of thedisc where such folded over portions are formed than in the remainingpart of the periphery, and in addition the groove in the disc, or theabutting faces of its parts, if a separable disc is used, produceharmful shocks against the workers hands. The exchange of the coating istime consuming and often injury may take place if the parts of aseparable disc have not been suificiently secured against accidentalseparation.

For a better utilisation of the abrasive material, a more uniform wearalong the whole periphery and for securing a more quiet grindingoperation methods have been devised for tensioning the abrasive layer bymeans of compressed air contained in a peripheral air chamber providedin the disc, for instance a rubber chamber. The greatest disadvantage ofsuch methods consists in this that for exchanging the abrasive coatingit is necessary to empty the chamber, and to inflate it again when thenew coating has been placed in position around the disc. The same effectmay be obtained by means of a device consisting of an yieldable rubberdisc of lozenge section the periphery of which may be expanded by twoplates exerting pressure against the said walls of the disc.

The disadvantage of this last mentioned ar- 2 Claims. (01. 51-191)rangement consists in this that the exchange of the abrasive coatings isslow, since it is necessary first to relieve the pressure acting on therubber disc and when a new coating has been placed in position, togenerate pressure anew by tightening one of the side plates.

An object of the present invention is to eliminate the disadvantages ofthe methods and devices referred to and to insure a very easy tensioningof the abrasive coating, a perfect utilisation of the abrasive materialand the possibility of a simple replacement of the worn out coatings.

The essential feature of the new method in accordance with the presentinvention consists in this that the abrasive coating which is mountedloose around the periphery of the disc, when the latter is arrested,becomes tensioned by the centrifugal internal stress on the elasticperiphery of the disc, when the latter is rotated. For this purpose theperiphery of the disc is provided with a hollow rubber ring of asuitable profile, the side walls of the ring being subjected to tensionby the centrifugal force acting on the peripheral part of the ring whenthe disc is rotated, whereby the abrasive coating is tensioned due tothe expansion of the circumference of the ring. Preferably thetensioning effect may be enhanced by partially filling the hollow spacein the ring with a suitable material in liquid condition or in the formof loose particles.

The accompanying drawing shows by way of example an abrasive disc inaccordance with the present invention in part sectional view.

The device in accordance with the invention comprises a metal disc Imounted in the usual way on a shaft 2 to which rotary motion is impartedin a manner known per se. The crown 3 of the disc I is provided oneither side with a groove 4 adapted to receive the corresponding flange5 of a rubber ring 6. The side walls I of the ring are thinner than itsperipheral part 8. A hole I0 may be bored through the crown 3 so as toopen in the hollow space 9 within the ring 6. The hole 10, which isclosed by a screw ll, may serve for supplying the hollow space 9 with asuitable liquid, such as oil or water or, if desired, with sand. Thespace 9 is filled in part only.

When the disc I is stationary a coating l2 of emery cloth or paper isplaced loosely around the periphery 8 of the ring 6. The coating I2 issupplied to the machine either ready in the shape of a hollow disc whichis threaded over the periphery of the rubber ring 6, or in the form of astraight strip of definite length which is 3 wound around the rubberring and then its ends are united, for instance by means of an adhesiveband placed underneath the ends of the abrasive strip.

When the shaft 2 with the disc I are rotated, the side walls 7 of therubber ring e are extended by the :efie'c-t .ofuth'e centrifugal'forceacting on the thicker peripheral part -8 of the ring, the periphery ofthe said ring being expanded at the same time to an extent determined bythe circumferential length of the emery coating. The centrifugal forceassisted by'the friction between the rubber ring and theemerycoating'isquite sufficient to retain the coating firmly onrthedisc. Under particularly severe conditions this efiect may be enhancedby filling the .hollow space -..9 within the rubber ring 6 in partwith-.oi1 which will increase the pressure exerted on the periphery 8 ofthe ring. When the abrasive coating has become worn out, the disc isarrested whereby "the periphery of the elastioring is contracted-and'1the coating may be readily removed and ;:replaced by a fresh one.

=WhatI claim is:

1. A rotary abrasive tool comprising a rigid wheel having a concentricannular groove in each side :face adjacent the periphery thereof, achannel shaped elastic ring member concentrically mounted-on said wheeland including a peripheral wall .and radially inwardly-extending sidewalls having inturned annular flanges rthereon engaged in the annulargrooves in the sides of said wheel, the distance from ,said flanges ftpthe ;peripheral wall of :said ring being greater .zthan-thendistance;from said grooves tothe periphcry of said wheel whereby the peripheralwall of said ring is spaced from the periphery of said wheel, saidperipheral wall of said ring constituting a seat and support for aninelastic band of abrasive material and adapted to retain the samethereon during operation by expansion of said ring due'to centrifugalforce.

2. An abrasive wheel according to claim 1 in which the space between theperiphery of the wheel and peripheral wall of the ring is partiallyfilled .with ,a heavy fluent material.

EMANUEL KRISTEK.

REFERENCES CITED The following references are of record in the :fileofthis patent:

"UNITED STATES PATENTS Number Name Date 23,571 Hale Apr. 12, 1859$172,287 Greoker Apr. 5, 1892 1 683122 Knill Sept. 24, 1-901.-l,:l8:6,058 Woods a June 6, 1916 2,072,129 :Rickseta-l. Mar. 2, 19.372,116,272 Ma-11 May 3, 1938 .'2,,221,1 73 Gutsell Nov. 12, 1940z2;2-36,-7Q9 :Hillix Apr. 1,11941 2,377,880 Gutsell June 12, .19452,432.;731 :De Haven. =Dec. 16, "1947 FOREIGN "PATENTS .Num-ber CountryDate 385,147 France". May/.2, .1908 430,687 Great Britain June 24, 1.935475,476 Great Br-itain Nov. 19,1937

